1. Field of the Invention
The present invention generally relates to a method of cleaning a semiconductor equipment, and more particularly, to a method of cleaning a reaction chamber.
2. Description of Related Art
In the semiconductor fabrication process, the inner surface of the reaction chamber of the semiconductor equipment would be contaminated after a period of operation, namely a deposition or an etching process. If the reaction chamber is not cleaned, the wafer processed within the reaction chamber would be contaminated. Thus, the fabrication yield is substantially reduced. Therefore, it is critical that the reaction chamber must be cleaned regularly.
Currently, the conventional method of cleaning the reaction chamber comprises two steps. First, a plasma gas containing NF3 gas is used to clean the contamination on the inner surface of the reaction chamber. Next, a protection film made of oxide is formed on the inner surface of the reaction chamber.
However, the protection film would also be formed simultaneously on an electrostatic chuck (E-chuck), which is adopted for carrying the wafers. The protection film formed on the E-chuck would stick on the back side of the wafer, and may peel off during the subsequent process and cause contamination. Accordingly, this may lower the fabrication yield rate and fabrication throughput.
In the prior art, a method for preventing the protection film from depositing on the E-chuck is to cover a ceramic wafer on the E-chuck. However, the ceramic wafer may break due to overheat conditions when depositing the protection film. In order to resolve the above problem, helium gas was guided into the E-chuck and exhausted through outlets of the E-chuck for reducing the temperature of the ceramic wafer. However, the helium gas exhausted from the outlets would cause uneven stress of the ceramic wafer and becomes tilted, and one end of the ceramic wafer may contact the E-chuck. Furthermore, abnormal black powders may be generated on the E-chuck due to the high temperature condition where the E-chuck comes in contact with the ceramic wafer causing wear and tear of the E-chuck.